The present invention concerns with oil, gas, petrochemical, coal and other industries, and specifically has to do with processing of heavy hydrocarbon materials (e.g. high-molecular-weight materials like crude oil, coal, etc.) for obtaining their light fractions having a low molecular weight (e.g. benzene, kerosene, fuels, etc. or getting liquid fuels from coal), typically by cracking or other types of converting of hydrocarbons.
The invention also addresses the issues of purification (e.g., removing sulfur contamination) from the treated hydrocarbon product during the cracking process. The most commonly used term for describing the process of treating raw hydrocarbon and its conversion into lighter, higher octane number components is refining. Petroleum refining has evolved continuously in response to changing consumer demand for new and better products. The original requirement was simply to produce kerosene as a cheaper and better source of light than whale oil. The development of the internal combustion engine led to the production of gasoline and diesel fuels. The evolution of the airplane first created a need for high-octane aviation gasoline and then for jet fuels, a much more sophisticated form of the original product, kerosene. Present-day refineries produce a variety of products including many required as initial materials for the petrochemical industry.
There are a few primary technologies that address the above needs. They include distillation, thermal cracking, catalytic conversion, and various other treatments. Of these, thermal cracking is considered to be the most efficient and universal technology, and it is commonly and broadly used for converting heavy high-molecular-weight hydrocarbons into lighter lower-molecular-weight fractions.
The objective of cracking hydrocarbons is to maximize output of desirable lower-molecular-weight products having minimum contaminants, while at the same time reducing power consumption. Advanced technologies of cracking high-molecular-weight hydrocarbons (e.g., heavy crude oil with high sulfur content or bitumens) attract significant attention worldwide.
In petroleum geology and chemistry, cracking is the process whereby complex organic molecules such as kerogens or heavy hydrocarbons are broken down into simpler molecules (e.g. light hydrocarbons) by the breaking of carbon-carbon bonds in the precursors. The rate of cracking and the end products in the traditional processes are strongly dependent on the temperature and presence of any catalysts. Cracking, also referred to as pyrolysis, is the breakdown of a large alkane into smaller, more useful alkenes and an alkane. Simply put, cracking hydrocarbons is breaking long chain hydrocarbons up into short ones.
Modern high-pressure thermal cracking operates at absolute pressures of about 7,000 kPa. An overall process of disproportionation can be observed, where light, hydrogen-rich fractions are formed at the expense of heavier molecules which condense and are depleted of hydrogen. The actual reaction is known as homolytic fission and produces alkenes, which are the basis for the economically important production of polymers.
A large number of chemical reactions take place during cracking, most of them based on free radicals. Computer simulations aimed at modeling what takes place during cracking have included hundreds or even thousands of reactions in their models. The main reactions that take place include:                Initiation reactions, where a single molecule breaks apart into two free radicals. Only a small fraction of the feed molecules actually undergo initiation, but these reactions are necessary to produce the free radicals that drive the rest of the reactions. Initiation usually involves breaking a chemical bond between two carbon atoms, rather than the bond between a carbon and a hydrogen atom.        Hydrogen abstraction, where a free radical removes a hydrogen atom from another molecule, turning the second molecule into a free radical.        Radical decomposition, where a free radical breaks apart into two molecules, one an alkene, the other a free radical. This is the process that results in the alkene products of cracking.        Radical addition, the reverse of radical decomposition, in which a radical reacts with an alkene to form a single, larger free radical. These processes are involved in forming the aromatic products that result when heavier feedstocks are used.        Termination reactions, which happen when two free radicals react with each other to produce products that are not free radicals. Two common forms of termination are recombination, where the two radicals combine to form one larger molecule, and disproportionation, where one radical transfers a hydrogen atom to the other, giving an alkene and an alkane.        
Presently known and commonly used petrochemical technologies of cracking hydrocarbons or getting liquid fuels from coal require high temperature, high pressure, and consumption of expensive short-lived catalysts. Thus, processes that occur in the reaction chamber are very difficult if not impossible to control. Besides, additional undesirable processes, such as polymerization, polycondensation and coking, usually accompany the cracking process. All presently existing technologies require high power consumption and are therefore expensive. Because of that, they are mostly practiced by only a few large-scale manufactures. Traditional petrochemical refinery plants are quite complex and occupy large territories. All above factors considerably limit usage of thermal cracking as a universal and cost-efficient technology.
One of the major factors affecting development of the world petroleum industry is the growing production of heavy oil having adverse physical and chemical properties (high viscosity, high boiling point, presence of undesirable contaminating substances, such as sulfur or others). Economically justified technologies for development of these resources have a very high strategic value for USA, Canada, Latin America, Middle East, Russia and other countries around the world. Here are a couple of typical examples of critical issues with oil processing:                It is highly advantageous to process heavy crude oil immediately after it's being produced, preferably at or near the well site, in order to reduce oil viscosity, density, sulfur contamination, etc. before transportation via pipelines. Otherwise, the ultimate cost of the final hydrocarbon product becomes very high;        At the entry of a petrochemical (refinery) plant it is often necessary, depending on properties of the raw input material, to modify crude product properties by some alteration of its chemical composition with the goal of increasing the content of saturated or non-saturated hydrocarbons, depending on specific requirements for further distillation process.        
Existing technologies of making liquid fuels from coal (e.g., gasification of coal or direct hydrogenation) require significant heating and high pressure. They are usually multi-cycle and high energy-consuming processes. Besides, these processes are very difficult to control and produce significant amounts of ecologically harmful waste.
All known methods of thermal cracking require continuous generation of free radicals—initiators of chain reactions. They require high temperature/high pressure environment and consume high dozes of the absorbed energy. This reduces efficiency of these methods and does not allow effective control of the process. Furthermore, some secondary detrimental processes (e.g., polymerization or coking) occur in the reaction chambers in most of the known technologies, which further reduces their value.
These known issues with the existing hydrocarbon cracking technologies prompt scientists and engineers worldwide to continue their search for new methods that are free of these disadvantages or they are less pronounced. The following is a brief summary of the related prior art that is published or otherwise publicly disclosed.
It is known in the art that under influence of ionizing radiation, both γ-rays and β-radiation, hydrocarbon molecular' destruction and polycondensation take place. In this case, the process development and resulting products depend significantly on the temperature and the absorbed doze of radiation that, in turn, determine a particular ratio between the pure thermal and combined thermal-radiation exposure during a cracking process of initial fractions (see for example Mustafiev I I Radiation-Thermal transformations of heavy oil and organic portion of petro-bitumen formation. “Chemistry of High Energies”, v. 24, No. 1, 1990, p. 22-26).
Another known technique is Electron-Radiation Thermal Cracking (ERTC). It is proposed for treatment and refining of oil and other hydrocarbon materials with the boiling temperature above 450° C. When such products are affected and treated by the beam of accelerated electrons, or Electron Beam (EB), with the energy of 1 to 4 MeV under atmospheric pressure and the temperature within the range of 400-410° C., the output of the desired end product increases significantly. In this case, the absorbed radiation dose is usually in the range from about 1 kGy to 10 kGy, kGy stands for kilo-Gray, a unit of the rate of radiation absorption, 1 Gray equals 1 joule per kilogram of mass. The efficiency of this process remains almost the same when the absorbed dose is increased above this range. The ERTC method was further modified: EB was proposed to be used to generate free radicals in the fluid; they, in turn, initiate chain reactions of heavy high-molecular-weight hydrocarbons' destruction (see Topchiev A V, Polak L S, Chernyak R Y, etc. // Academy of Science, USSR, 1960, v. 130, p. 789). This modified version of ERTC is more effective at lower temperatures of the liquid phase, and it does not require catalysts (see SELF-SUSTAINING CRACKING OF HYDROCARBONS, International patent publication No. WO 2007/070698).
It is also known that in a gas phase it is possible to create electric discharges, during which various plasma-chemical reactions take place. For supporting non-equilibrium plasma-chemical processes that occur at lower temperatures, the use of electric discharges with a low degree of gas ionization are of the primary interest. An example of this is sub-microsecond pulse-frequency corona discharges that take place in gases and liquids as described by Piskarev I M, Ushkanov V A, Selemir V D, etc. “Mixing a liquid under influence of a nanosecond corona high-current electric discharge”, Scientific eMagazine <<Researched in Russia>>.
Another example of the prior art methods is a non-self-sustaining electric discharge occurring in a gas affected by an external ionizer of a very high intensity, such as an Electron Beam. An electric field of high intensity superimposed on the gas that, in turn, is exposed to the EB multiplies a number of electrons generated due to EB, and creates an electric discharge, which generates chemically active particles. Numerous applications of these discharges in homogeneous media are well known (e.g., for activating gas lasers). For example, chemical activity of an electric discharge supported by EB in a homogeneous gas is described in Y N Novoselov, V V Ryzhov, A I Suslov // Letters in Journal of Theoretical Physics, 1998. v. 24. No. 19; p. 41.
All of the above mentioned references are incorporated herein in their entirety by reference.
Once the basics of the cracking method are established, it can usually be used in reverse, namely to unify light fractions of hydrocarbons into a heavy hydrocarbon.
Therefore there is a need for an improved thermal cracking process allowing reducing energy consumption and reducing production of contaminants along with the desired product.